Serum Anti-Ro52/Tripartite Motif-containing 21, A Novel Criterion of Interstitial Pneumonia With Autoimmune Features

Background: Antibodies to Ro52/tripartite motif-containing 21 (TRIM21), referred to as anti-Ro52, are found in patients diagnosed with diverse systemic autoimmune rheumatic disease and associated with interstitial lung diseases. However, little is known about the clinical characteristics of anti-Ro52 in patients with idiopathic interstitial pneumonias (IIPs). We aimed to analyze the prevalence, co-existent autoantibodies, and clinical characteristics of anti-Ro52 in patients with IIP. Methods: : The study enrolled 288 patients diagnosed with IIP. Serum anti-Ro52 was detected using enzyme-linked immunosorbent assay (ELISA). Co-existent autoantibodies, including anti-aminoacyl-tRNA synthetases (anti-ARS), were analyzed by immunoprecipitation. ELISA using recombinant antigens was performed as needed. Clinical, laboratory, and radiographic findings and survival of IIP patients were compared between anti-Ro52 positives and negatives. Results: : Anti-Ro52 (20/288; 6.9%), anti-ARS (18/288; 6.3%), and anti-Ro60/SS-A (16/288; 5.6%) were the most common autoantibodies detected in IIP patients. Among 20 IIP patients who had anti-Ro52, anti-ARS was present in 8 (40%), and anti-Ro60/SS-A was found in 6 (30%) patients. The criteria for interstitial pneumonia with autoimmune features (IPAF) were significantly better fulfilled by patients with anti-Ro52 than those without (P = 0.001). Meeting serological domain (P < 0.001) and Raynaud’s phenomenon (P = 0.009) were significantly more common in the anti-Ro52-positive patients. There was no significant difference in the overall survival rate of IIP patients with vs. without anti-Ro52 (log-rank P = 0.51). Conclusion: Anti-Ro52-positive IIP patients have clinical features consistent with IPAF. Adding anti-Ro52 in IPAF criteria may be considered in the future.